Production of high octane gasolines



PRODUCTION OF HIGH OCTANE GASOLINES Filed April 13, 1946 1- OLEF/NJ 9 z OLEF/NJ x C5 HYDROKARBONS ISOMEFf/ZER I 4 1-OLEF/IV5 F/RST GASOLINE GASOL/NE a 0L [SF/N5 SECOND PASS TREATMENT IN V EN TOR.

- ATTORNELS Patented Jan. 20, 1948 UNITED STATES PATENT OFFICE PRODUCTION OF HIGH OCTAN E GASOLINES John R. Bates, Swarthmore, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application April13, 1946, Serial No. 661,996

4 Claims. 1

. tion, or pass, under certain conditions, whereby the octane value of the gasoline can be significantly increased.

This invention is concerned with an improvement in processes wherein a first pass gasoline having relatively low octane value is treated in a second pass at an elevated temperature and under pressure to modify the chemical constitution thereof, at least in part.

Now, it is known that hydrocarbons of h gh anti-knock value are obtained when the carbon atoms are arranged compactly.

According to the invention, a first pass gasoline is subjected to conditions which will cause isomerization of olefins present to others which will enable the production of more highly branched paraffins in the second pass or treating step. Thus, by the isomerization of, say, l-olefins to 2-olefins in the first pass gasoline, prior to subjecting the same to the second pass treatment, there will be obtained in said second treatment a final fuel product having a higher octane value or rat ng than it would have had otherwise. .The isomerization of l-olefins to 2-olefins can be caused by operating upon the whole gasoline or .it may be caused by treatment of a portion thereof.

l-olefins are usually lower boiling than 2- olefins. Thus, for example, a deisopentan zed C-5 hydrocarbon fraction of a debutanized first pass gasoline can be separated by distillation into a portion consisting substantiall of l-olefins and a portion consist ng substantially of 2-olefins. That is, the boiling points of the l-oleflns and 2-o1eflns are sufficiently d fferent to allow the sep ration by distillation. I have found that the bo ling points of the l-olefins in a C-5 fraction are lower than the lowest boiling 2-olefins. The tab e following shows the boiling points of the various C-5 hydrocarbons including pentane:

Table C 3-Methyl butene-l C( 3O=C 20.1 68

C Isopentane C-O( JC 27.9 82

Pentene-l CC-C-O=C 30.1 86

C 2-Methylbutene-l CC( J=C 31.0 88

Pentane COCC-O. 36.1 97

n-Pentene-2 CC-C=C-O 36.4 97.5

C 2-Methyl butene-2 O-C=-C 38.4 101 Inspection of the foregoing table shows that the l-olefins can be separated from the 2-olefins. Pentane can be allowed to pass through the second pass treating zone or can be removed as desired it being Within the scope of this invention to dispose of pentane in any Well known manner.

Therefore, instead of operating upon the whole gasoline to cause isomerization of l-olefins to 2- olefins therein, according to the invention the more volatile portion of first pass gasoline, which consists substantially of C-5 hydrocarbons, can be treated to isomerize l-olefins to 2-olefins. The 2-olefins are then combined with the gasoline and the combined gasoline is subjected to the second pass treatment. The unisomerized l-olefins can be returned for further isomerization treatment until the l-olefin content of the C-5 hydrocarbon fraction has been exhausted.

In order to more fully set forth the invention, reference is made to the drawing which illustrates schematically a preferred embodiment thereof. A debutanized first pass gasoline resulting from the treatment of heavy stocks is passed by means of conduit 2 into a fractionator 3 wherein the more volatile portion consisting of C-5 hydrocarbons is separated therefrom. This portion is passed through conduits 4 and 5 into fraction ator 6 wherein the 0-5 hydrocarbons are separated into l-olefins and 2-oleflns, respectively, preferably with elimination from the process of any isopentane. The l-olefins are 2 methyl butene-l, 3 methyl butene-l and pentene-l and the 2-olefins are 2 methyl butene-2 and npentene-2. l-olefins are taken overhead through conduit I into isomerizer 8 wherein isomerization of 2-olefins is caused. The efliuent from isomerizer 8 contains equilibrium concentrations of l-olefins and 2-olefins and is passed by means of conduits 9 and into fractionator 6 wherein lolefins and 2-olefins are separated. 2-oleflns are passed by means of conduit l0 into conduit H wherein these are mixed with the gasoline which is passed from the bottom of '-'f-ractionator -3 through conduit H to the second pass treating zone l2. The final product is withdrawn from the unit through conduit l3.

The conditions required for the isomerization are known in the art. For example, l-pentenes can be passed over a catalyst :prepared by treating bauxite with sulfuric acid. The temperature in the isomerizer can be in the neighborhood of 300 F. or higher. Other catalysts adapted to isomerize l-olefins to 2-olefins are Within the scope of the invention.

The conditions required for the second pass treatment of gasoline arealso known in the art. For example, a temperature in the range 800 F.- 875 F., a pressure in the range 25 lbs/sq. in. gauge-100 lbs/sq. in. and a siliceous catalyst can be employed. Other conditions of second pass treatment with or without a catalyst are not excluded from the scope of the invention.

It will be obvious to those skilled in the art that the invention is applicable to the treatment in the isomerization step of, for example, hexene- 1 to isomerize it to hexene-Z and then combining the 'hexene-2 with the gasoline prior to second pass treatment thereof.

The followin example is illustrative of the invention:

Example A heavy gas oil of suitable boiling range can be reacted over a catalyst to .produce a debutanized gasoline with approximately 40% yield. The pentane fraction of this gasoline will contain approximately 50% .olefins. The pentenes are separated into two fractions by distillation one containing substantially .all l-pentenes and the other the 'Z-pentenes. The l-pentene fraction is isomerized by recycle isomerization until it is converted to the higher boiling 'LZ-pentenes. The originally occurring 2-.pentenes plus the isomerization product are combined with the gasoline. The gasoline blend thus obtained is charged to a catalyst consisting preferably of a silica-alumina mass substantially free of sodium and of high activity at about 840 and about '75 lbs/sq. in., witha liquid-charge rate of about 1.2 volumes/hour/vol. of catalyst to obtain areaction product.

This reaction product can be separated into gaseous fractions consisting of butanes and lighter boiling, and an aviation cut of high octane number and good susceptibility to tetraethyl lead. The materials boiling higher than aviation gasoline (300 F.) are high quality motor fuel and a small amount of fuel oil.

Variation and modification are possible within the scope of the invention the essence of which is that l-olefins comprised in a first pass gasoline are isomerized to 2-olefins therein, or apart therefrom, prior to second pass treatment thereof, followed by second pass treatment of said gasoline.

I claim:

1. A process of producing an improved gasoline which comprises treating a gasoline, derived by cracking of a petroleum oil in a first pass, to isomerize l-olefins to 2-olefins therein and then subjecting the gasoline in which the l-olefins have=been isomerized to 2-olefins to a second pass cracking treatment.

-2. .A process of :producing an improved gasoline which comprises treating a gasoline, derived by cracking of a petroleum oil in a first pass, containing a l-pentene to produce an improved gasoline therefrom which comprises separating said l-pentene from said gasoline, isomerizing said l-pentene to a Z-pentene, combining the 2-pentene with said "gasoline and then subjecting s'aid gasoline to a second pass cracking treatment.

3. A process for producing an improved ga'soline which'com prises treating a gasoline, derived by cracking '01 a petroleum oil in a first pass, to isomerize 1 olefins :to 2 olefins therein and subjectin'g said inst pass gasoline in which the '1- olefins have been iis'om'erized to 2-0lefins under pressure and at an elevated temperature to a second pass cra'ckin'g treatment.

4. A process for producing an improved (ga's'oline "which comprises treating, a gasoline, derived by cracking of as petroleum fan in a first pass and containing :a l-p'enten'e, to produce an improved gasoline therefrom which comprises se arating said lp'en'te'n'e from said first pass gasoline, isomerizing said l-pentene to a z pentene, combining'theQ-pentene'withsaid firs't pass gasoline and 'then subjecting said first pa'ss gasoline under pressure and at an -leva't'e'd temperature to a second pass cracking treatment.

JOHN BATES. I

REFERENCES CITED The following references are of record in the file of this patent:

Peterson et a1. May '8, 1945 

